Five million heart failure patients in the US have poor cardiac pumping due to irreversible damage of the contractile myocytes. Thus, recovery of cardiac function by cell and tissue engineering is highly desirable. The novel approach proposed in this application combines bioengineering and cell biology-based techniques to directly target the regeneration of heart muscle, which is an important clinical problem not well addressed by current therapies. We have systemically delivered an artificial stabilized form of the mechano-growth factor (MGF), (24 amino acid, E-domain peptide from the prohormone) that is a member of the insulin-like growth factor (IGF) family and shown recovery of function in failing mouse hearts along with the mobilization of resident progenitor cells. We take advantage of the natural repair capacity of the heart by providing a microrod scaffold (MRS) to not only deliver the native, rapidly degradable MGF, but also provide local mechanical and topographic cues necessary for proper cellular connectivity and differentiation. Our overall hypothesis is that timed release of MGF and IGF-1 delivered locally by the MRS regenerates and strengthens the damaged myocardium without harmful side effects. This is tested on progenitor/stem cells and cardiac myocytes in culture and in animal models. Specific Aim 1 determines the effect of stiffness variation on cells grown in 3D microrod scaffolds. We optimize MRS characteristics for regulation of cell proliferation, lineage commitment, differentiation, contractile maturity and connectivity of stem cells and cardiac myocytes. Specific Aim 2 determines the effect of growth factor (GF)-loaded MRS in environmental conditions that mimic the normal and ischemic heart. We characterize encapsulation efficiency, GF biostability, and acellular release kinetics of the eluting MRS in vitro. We determine effects of GF release from MRS on proliferation and migration of progenitor/ stem and neonatal rat ventricular myocytes to establish changes in gene expression and cell survival under culture conditions that mimic the normal and ischemic heart. Specific Aim 3 determines the cellular, molecular and functional gains that occur at different stages following myocardial infarction after MRS delivery of GFs to the border zone of an infarct. We examine how GF release affects the migration and differentiation of cardiac progenitor cells in vivo. We examine the beneficial effects of localized MGF peptide delivery on cardiac function, prevention of cardiac myocyte apoptosis, prevention of adverse cardiac remodeling, and reduced scar formation. Our long-term goal is to develop microrod MGF therapy that supports the regeneration of cardiac muscle to regain cardiac function in the failing human heart. Public Health Relevance Statement (provided by applicant): Heart failure is a common condition carrying a high burden of disability and mortality. Current estimates are that heart failure accounts for approximately one million hospitalizations and $10 billion in health care costs in the United States per year. The main underlying causes of heart failure are ischemic heart disease, hypertension and idiopathic dilated cardiomyopathy, whose common pathophysiologic characteristic is an inadequate mass of functional myocytes. This proposal develops and tests a novel therapeutic 3D eluting microrod scaffold (MRS) system to deliver a natural cardiac growth factor for aiding in the regeneration and recovery of damaged cardiac muscle in culture and animal models.